It was first predicted to exist in the 1960s but, much like the Higgs boson particle before it, the pentaquark eluded science for decades until its detection at the LHC.
The discovery, which amounts to a new form of matter, was made by the Hadron Collider’s LHCb experiment.
The findings have been submitted to the journal Physical Review Letters. In 1964, two physicists – Murray Gell Mann and George Zweig – independently proposed the existence of the subatomic particles known as quarks.
They theorised that key properties of the particles known as baryons and mesons were best explained if they were in turn made up of other constituent particles. Zweig coined the term “aces” for the three new hypothesised building blocks, but it was Gell-Mann’s name “quark” that stuck.
This model also allowed for other quark states, such as the pentaquark. This purely theoretical particle was composed of four quarks and an antiquark (the anti-matter equivalent of an ordinary quark).
New states
During the mid-2000s, several teams claimed to have detected pentaquarks, but their discoveries were subsequently undermined by other experiments.
“There is quite a history with pentaquarks, which is also why we were very careful in putting this paper forward,” Patrick Koppenburg, physics co-ordinator for LHCb at Cern, told BBC News.
“It’s just the word ‘pentaquark’ which seems to be cursed somehow because there have been many discoveries that were then superseded by new results that showed that previous ones were actually fluctuations and not real signals.""
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